The endogenous opioid system is thought to play an important role in mother-infant attachment. In infant rhesus macaques, variation in the μ-opioid receptor gene (OPRM1) is related to differences in attachment behavior that emerges following repeated separation from the mother; specifically, infants carrying at least one copy of the minor G allele of the OPRM1 C77G polymorphism show heightened and more persistent separation distress, as well as a pattern of increased contact-seeking behavior directed towards the mother during reunions (at the expense of affiliation with other group members). Research in adult humans has also linked the minor G allele of the analogous OPRM1 A118G polymorphism with greater interpersonal sensitivity. Adopting an interactionist approach, we examined whether OPRM1 A118G genotype and maternal (in)sensitivity are associated with child attachment style, predicting that children carrying the G allele may be more likely to develop an ambivalent attachment pattern in response to less sensitive maternal care. The sample consisted of 191 mothers participating with their children (n = 223) in the Maternal Adversity, Vulnerability and Neurodevelopment (MAVAN) project, a community-based, birth cohort study of Canadian mothers and their children assessed longitudinally across the child’s development. Maternal sensitivity was coded from at-home mother-child interactions videotaped when the child was 18 months of age. Child attachment was assessed at 36 months using the Strange Situation paradigm. As predicted, G allele carriers, but not AA homozygotes, showed increasing odds of being classified as ambivalently attached with decreasing levels of maternal sensitivity. Paralleling earlier non-human animal research, this work provides support for the theory that endogenous opioids contribute to the expression of attachment behaviors in humans.

Optical textures pictured in the seminal 1974 textbook, The Microscopy of Liquid Crystals, by Norman Hartshorne, have been reappraised. Some of these, which were described by Hartshorne (and many others) as confused focal conics, were of chromonic and discotic phases, which had not been identified at that time—and would now be recognized as developable domain structures of columnar phases. It is suggested that the rigorous constraint of isometry in these is relaxed in regions of the director field under high stress. A rationale for the characteristic striated appearance of columnar textures is proposed, in which the molecular columns are bundled together, forming twisted ropes within the domains. It is also suggested that the regular alternation of opposing domains in M ribbons minimizes the slippage of columns required as the mesophase develops, and an explanation of the characteristic multi-pole appearance of the brushes in the optical textures of columnar structures is proposed.

Isotropic phase de-wetting of discotic liquid crystals on a surface patterned with alternating similar to 5-10 mu m wide wetting and de-wetting stripes results in the formation of long narrow droplets. On slow cooling into the columnar phase, the liquid crystal aligns such that the columns lie either across or along the stripes. However, if the stripes are wider and/or the cooling rate is too fast, defects appear. When there are many such defects, the result is complex zigzag and wavy line optical textures, which are reminiscent of the egg and dart friezes associated with classical architecture. To a first approximation, all of these patterns can be seen as joined up fragments of developable domains in which the columns either circle a defect or propagate in a straight line. They are built up from motifs that involve bend but not splay or twist deformations; deformations that leave the two-dimensional lattice of the columnar phase unchanged. As is shown, these basic circular and straight-line motifs can be combined in a variety of different ways along the stripe but, in all of these, it is found that the defects alternate from side to side. [GRAPHICS] .

A recent paper by Chan and Coen (March, 2020) proposes a dual mechanism hypothesis for the orientation of cellulose microfibrils in plant cell walls. One of these is an autonomous mechanism, which takes place outside the plasma membrane, within the cell wall itself (a). The other is the more complex microtubule-guided cellulose alignment process, where the orientation of microfibrils is directed by microtubules within the cell, via trans-membrane protein complexes (rosettes) (b). This mechanism can override the autonomous process and, it is argued, can explain how the production of complex detailed multi-layer alignment patterns of secondary walls is orchestrated. This paper concerns the latter process. It pushes the model one stage further back, by proposing a mechanism for the initial alignment of microtubules, in terms of the liquid crystalline state of the cortex. Justification for the hypothesis is given in terms of the in-vitro observations of the liquid crystalline mesophase formed by microtubules, and of the self-ordering properties of liquid crystalline systems in general. As an example, the production of a plant cell wall with a helicoidal array of cellulose microfibrils is pictured in some detail.

There is a strategic difference between the process of cell division by mitosis in animal cells and that in cells of higher plants. One particularly puzzling feature is the absence of centrioles in plant cells, when they appear to be of central importance in the control of the process in animal cells. It is argued that in both cases the dividing cell uses the versatility of the liquid crystalline state of the mitotic cytoplasm created by the wide-scale assembly of microtubules prior to mitosis. It is not the centrioles per se which are vital - it is the director field of the mesophase which is crucial - and alternative procedures have been developed by plants and animals to create this. In both cases, they can be related to known spontaneous alignment states of liquid crystalline systems.

Nanoscale phase separation and self-organisation in liquid crystals leads to the formation of remarkable hierarchical structures. There are several examples of heliconical nanofilament structures including in the nematic twist-bend (NTB) phase, the B4 phase and liquid crystal gels formed from the B4 phase. Both the formation of the polymer-like structures that permeate the soft-solids and their hierarchical structures are fascinating, not least because of the analogies that can be drawn with naturally-occurring structures. Here, we report a remarkably simple binary system formed from a non-symmetric BC molecule and the rod-like liquid crystal, 5CB. The pure bent-core system exhibits both nematic and dark conglomerate liquid crystal phases. At very low concentrations of the BC material (5-10%) this binary system spontaneously self-assembles into a soft solid formed from nanoscale filaments that are aligned by their nematic environment. Macroscopically, the soft solid shows behaviour that can be associated with both polymers and gels. Interestingly, the sub-micron scale structure of the filaments appears remarkably similar to some organised fibrous structures in nature (e.g. chitin, cellulose, insect cuticle, plant cell walls) something we attribute to self-assembly and self-organisation in an aligned liquid crystalline environment. The nanoscale structure of the filaments shows no features that can be associated with heliconical ordering down to length scales of tens of nanometers. However, the X-ray data suggest that a metastable rectangular columnar phase which is highly ordered in one dimension initially forms, changing to a hexagonal lattice on a timescale of tens of minutes.

ABSTRACT The optical texture of the nematic phase, variously known as the schlieren, structure à noyuax or nucleated domain texture, was identified over a century ago as being an array of point singularities. When viewed between crossed polars, patterns of dark brushes radiate from each point nucleus. The sign and strength of each nucleus can be uniquely determined from the changes in the orientation of these brushes when either the sample or the crossed polars are rotated, from two formulae given by Chadrasekhar in 1977. However, these were given with little exemplification and have been largely overlooked. Consequently, the majority of the discussions given in current literature are either incomplete and confusing or, in some cases, incorrect. Here, we provide a detailed explanation of the textures and their behaviour as viewed with the most commonly used experimental geometry (i.e. with a rotating sample and stationary polars). Graphical Abstract

IntroductionMaternal mental well being influences offspring development. Research suggests that an interplay between genetic and environmental factors underlies this familial transmission of mental disorders.ObjectivesTo explore an interaction between genetic and environmental factors to predict trajectories of maternal mental well being, and to examine whether these trajectories are associated with epigenetic modifications in mothers and their offspring.MethodWe assessed maternal childhood trauma and rearing experiences, prenatal and postnatal symptoms of depression and stress experience from 6 to 72 months postpartum, and genetic and epigenetic variation in a longitudinal birth-cohort study (n = 262) (Maternal adversity, vulnerability and neurodevelopment project). We used latent class modeling to describe trajectories in maternal depressive symptoms, parenting stress, marital stress and general stress, taking polygenetic risk for major depressive disorder (MDD), a composite score for maternal early life adversities, and prenatal depressive symptoms into account.ResultsGenetic risk for MDD associated with trajectories of maternal well being in the postpartum, conditional on the experience of early life adversities and prenatal symptoms of depression. We will explore whether these trajectories are also linked to DNA methylation patterns in mothers and their offspring. Preliminary analyses suggest that maternal early life adversities associate with offspring DNA methylation age estimates, which is mediated through maternal mental well being and maternal DNA methylation age estimates.ConclusionWe found relevant gene-environment interactions associated with trajectories of maternal well being. Our findings inform research on mechanisms underlying familial transmission of vulnerability for psychopathology and might thus be relevant to prevention and early intervention programs.Disclosure of interestThe authors have not supplied their declaration of competing interest.

IntroductionAnimal and human studies suggest that individual differences in maternal parenting behaviour are transmitted from one generation to the next.ObjectiveThis study aimed to examine potential psychosocial mechanisms underlying an intergenerational transmission of conceptualization of parenting, including affect, cognition, and parental support.MethodsIn a subsample of 201 first-time mothers participating in the Maternal Adversity, Vulnerability and Neurodevelopment (MAVAN) project, we assessed maternal childhood rearing experiences, using the Parental Bonding Instrument and the Childhood Trauma Questionnaire. At 6 months postpartum, mothers completed questionnaires on parenting stress, symptoms of depression, internalization of maternal care regulation and current relationship with mother and father.ResultsWe found significant direct associations of maltreatment and rearing by the grandmother with parenting stress at 6 months. These associations were mediated through distinct psychosocial pathways: the association of maltreatment on higher parenting stress was fully mediated through more maternal symptoms of depression (z = 2.297; P = 022). The association between sub-optimal rearing provided by the mother and higher parenting stress was mediated through lower internalization of maternal care regulation (z = -2.155; P = 031) and to a lesser degree through more symptoms of depression (z = -1.842; P = 065). Finally, higher quality rearing by the grandfather was indirectly related to lower parenting stress through positive current relationship with the father (z = -2.617; P = 009).ConclusionsThere are distinct pathways by which early experiences manifest in parenting stress. By understanding the structure of dysregulated parenting, clinicians will have practical information to specifically target maternal motivation, social supports, and depressed mood to disrupt maladaptive parenting cognitions and practices.Disclosure of interestThe authors have not supplied their declaration of competing interest.

The curfew tolls the knell of parting day1The weary George plods homewards o’er the leaNight falls upon the lab of G W GrayAnd leaves the world to darkness and to me. Far from the madding crowd’s i...

4 Silk and Fibers, Collagen Volume 7. Supermolecular and Polymeric Liquid Crystals Part I. Liquid Crystals in Biological Structures John Lydon, John Lydon University of Leeds, The Faculty of Biological Sciences, West Yorkshire, Leeds LS2 9JT, UKSearch for more papers by this author John Lydon, John Lydon University of Leeds, The Faculty of Biological Sciences, West Yorkshire, Leeds LS2 9JT, UKSearch for more papers by this author First published: 08 February 2014 https://doi.org/10.1002/9783527671403.hlc107Citations: 1 Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. 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This is an account of the study of the strange little mesogen, diisobutylsilane diol, at Leeds in the 1970s and the role which George Gray played in the story. Even in those early days George imposed a quiet authority on the subject. In both Britain and abroad, people listened to him and valued his opinions and judgment. He steadily assumed the elder statesman role in the British liquid crystal world. He was always accessible and ready to help people like me who were not in his own research group.

Abstract Chromonic systems are the lyotropic analogs of the thermotropic columnar mesophases. They are formed by soluble aromatic compounds, typically with between 3 and 10 fused aromatic rings. The molecules have aromatic cores with solubilizing hydrophilic groups around their peripheries. The basic structural units in these systems are elongated stacks of molecules (rather than individual molecules or micellar assemblies). There are two common chromonic phases; a more dilute phase consisting of a nematic array of columns (the N ‐phase) and a more concentrated phase in which the columns lie in a hexagonal array (the M ‐phase). Chromonic phases are formed by a range of compounds, including drugs, dyes, and nucleic acids. They have distinctive optical textures and characteristic multiperitectic phase diagrams (in contrast to the multieutectic phase diagrams of conventional amphiphiles). Some antiallergic and antiasthmatic drugs and many commercial dyes have proved to be chromonic, but the ability to form liquid crystalline phases appears to be incidental to their dyeing and medicinal properties. However, recent studies have shown that the combination of self‐ordering, ease of alignment, sensitivity to changing conditions and additives, coupled with their optical and electrooptical properties, gives these systems unique and potentially valuable properties – and it is expected that these will lead to a new generation of applications. It is predicted that there will be increased emphasis on the development of a range of sophisticated devices, either produced from or actually incorporating chromonic phases. These include polarizers, optical compensators, light‐harvesting devices, and biosensors for medical diagnosis.

An optical micrograph taken by R. J. Bushby and co-workers using crossed polarizers shows a thin film of 1,4,8,11,15,18,22,25-octaoctylphthalocyanine in its columnar rectangular liquid crystal phase at 100 °C. In such thin, open-to-the-air films, the columns are aligned in-plane but follow random sweeping lines. However, when open-to-the-air films are confined within micrometer-scale channels formed from SU8, all of the columns are aligned and point in the same direction, as shown on page 5997.

A range of triphenylene and phthalocyanine-based discotic liquid crystals (DLCs) can be aligned within micrometer-scale channels formed from SU8 patterned on silicon or glass surfaces. The channels can be filled with the DLC in its isotropic phase using capillary action. Alignment occurs spontaneously as the sample is slowly cooled into the Col(h) phase. Whilst all of these DLCs align with the columns perpendicular to the surface when they are sandwiched' between glass slides, in these channels, the DLC aligns with the column director parallel to the surface. It is also constrained to lie across the channels. The same alignment occurs when these DLCs are confined between SU8-topped interdigitated gold electrodes where it gives the optimum orientation for electrode-to-electrode conduction. The quality of the alignment depends on the particular liquid crystal used and on the width of the channel. For the Col(r) phase of octaoctylphthalocyanine there is additional epitaxial control over the orientation of the lattice such that the a/c face of the lattice is parallel to the surface. This is an important prerequisite for creating a bistable display device that switches by virtue of changing the direction of the tilt of the discs.